1. Field of the Invention
This invention relates generally to a container inspection system, and is directed more particularly to a container inspection system which enables high speed and reliable discrimination for the good or bad of objects such as containers and the like to be detected or inspected.
2. Description of the Prior Art
Conventionally, the judgement for the internal pressure or inspection of the good or bad of sealed containers such as canned products, was widely dependent on the tapping inspection which relies upon the hearing ability of mankind (sensitivity inspection), whereas during the recent years, methods to inspect the cans by electrical energy or signal transmitted onto the cans to cause vibration of the can and thereby taking measurement of the energy distribution of various frequencies of the electrical signal caused by the vibration of the cans to detect whether the cans are good or not are proposed.
However, by such methods, by the delicate differences such as wall thickness of the can or the rotary sealing degree of the caps of bottles, the energy distribution of the various frequencies are influenced, and further when relatively large electrical energy impacts are given to the containers such as cans, a harmful noise other than the container's inherent resonance frequency is simultaneously generated, which makes it difficult to extract the correct electrical signals related to the internal pressure of the container such as cans and consequently, by the above or conventional methods, there is a drawback where it is impossible to conduct an accurate inspection.
Normally, to erase a noise or to extract the peculiar energy of various frequencies, a complicated electrical processing which requires long processing time is required. Accordingly, by such above mentioned known technology the discrimination of the good or bad of the produced cans that flow on a high speed conveyer remains improper for adoption.